Typically, in an automated factory, precise measurements of manufacturing and processing are invaluable to the efficiency of the manufacturing process and the quality of the products produced. Ideally, devices used for holding and placing products or component parts to be processed in a robotic operated factory need to be automatically operated to facilitate hands-free operations or eliminate human interventions as much as possible. This improves the speed of manufacturing or processing time and reduces injury to, or mistakes by, human operators. In this way, an automated factory ultimately produces higher quality products at lower manufacturing cost, which tends to increase profits to companies or reduce cost to consumers allowing domestic companies to be more competitive in world markets.
Usually, an automated factory produces high quality products by using the latest available technology in its internal manufacturing operations. However, a company focusing only on its own product manufacturing capabilities will not maintain its competitive edge for a sufficiently long time. That is, although it is important to achieve superiority in its internal manufacturing operations, to be a true leader, companies must be aware that products purchased from outside vendors may not always conform to the higher quality standards of their internal factory operations. With this awareness, it is of paramount importance to design for a reasonable variation in goods purchased from outside vendors. In this way, time-consuming operations are avoided when products vary without their design tolerances.
Especially in robotic end-effectors, for example, a multi-functional end-effector must have a reasonable tolerance built in to compensate for variations in components size or over-travel by individual end-effectors, etc. Typically, this tolerance is accomplished with the aid of springs, which allow the end-effectors to vary within a limited range when there is an inadvertent contact by an end-effector on a component or part. Unfortunately, to increase or decrease the range of variation, the spring must be changed to precisely match the new desired range because variation in the range produces substantial variation in the force being applied to the components to be picked up and placed. Also, springs subjected to high mechanical stress from continuous use will often fail because of metal fatigue.
Accordingly, a need exists for a quick and efficient method and apparatus for compensating for variations which permits placement operations at several different vertical positions while maintaining the same placement force on the component parts being placed.